Preparation of saturated hydrocarbons



April 6, 1948. H. T. QUIGG 2,439,021

PREPARATION 0F SATURATED HYDROCARBONS Filed July 24, 1945 ATTORNEYSPatented Apr. 6, 1948 PREPARATION F SATURATED HYDROCARBONS Harold T.Quiza', Bartlesville, 0kla.-, assignor to Phillips Petroleum Company, acorporation oi' Delaware Application July 24, 1945, serial No. soasesThis invention relates to the preparation of l paralns or saturatedhydrocarbons from lowboiling normally gaseous oleiins, and especiallyfrom ethylene or ethylene and propylene, contained in normally gaseousstreams such asthe eiluent from an ethane and/or propane cracking unitor the cracked gas formed as a by-product in cracking operations. Y Moreparticularly it relates to the conversion of such low-boiling aliphaticolen's into higher-boiling parafiins in the motor and/or aviation fuelrange of boiling point and molecular weight. Still more particularly, itrelates to a process wherein the ethylene contained in cracked gasstrea/ms is converted to valuable paraflinic hydrocarbons, especiallybranched chain octanes, suitable for use as a high knock rating blendingcomponent in the preparation of aviation and motor fuels.

The 'art of converting butylenes. by alkylation of isoparafiinsespecially isobutane, to high octane hydrocarbons is well known. It isalso well known that the conventional alkylation catalysts such ashydrofluoric acid and sulfuric acid will not effect alkylation withethylene. Special catalysts such as aluminum chloride are required tobring about alkylation of isoparaillns with ethylene. 'I'he alkylationof isobutane with ethylene by means of aluminum chloride-containingcatalysts produces Cs hydrocarbons, especially diisopropyl. However, noeconomically feasible process is available whereby aliphatic oleiinsboil- 11 claims. (el. zooi-683.4)

ing below butylenes, such` as propylene and more especially ethylene,can be reacted with isoparailins to give parains heavier than C1, suchas the branched chain octanes, nonanes and higher parafflns. .Sincetremendous quantities of ethylene and propylene are cheaply and readilyavailable in dilute form in cracked gas streams, such a process ishighly desirable.

The principal object of my invention is to make available to the art aprocess whereby low-boiling oleiins, especially propylene and moreparticularly ethylene, can be converted to heavier saturatedhydrocarbons of motor and aviation fuel and heavier boiling range,predominantly Ca and heavier, in a simple and economical manner. Anotherobject is toprovide a process of the -foregoing type which involves aminimum number of steps and gives a high yield of valuable products witha minimum of loss by undesirable side reactlons and the like. Anotherobject is to provide an improved method of converting olefins containedin waste refinery gas streams into valuable products. Another object isto provide a process of the foregoing type which gives a high yield ofhigh octane number Cs and heavier hydrocarbons from an oleiin-containingstream whichcontains relatively small amounts of propylene. process lasin the foregoing objects which does not require an expensive preliminaryconcentration of ethylene or ethylene and propylene contained in thecracked gas stream used as starting material. Another object is toprovide a process of the foregoing type which gives a more desirableproduct than is obtained from other processes using light olens, such asethylene, as the raw material. Numerous other obiects will appear morefullyhereinafter.

The accompanying drawing portrays diagrammatically one arrangement ofequipment which has been found suitable for carrying out the process ofthe present invention.

General In accordance with my invention, normally gaseous olefinscontained in a normally gaseous mixture containing other normallygaseous components, especially hydrogen 'and parafiins includingmethane, are converted into heavier hydrocarbons in the motor andaviation fuel range of molecular weight and boiling point by threesequential steps which are integrated into a unitary process. Theoleiins are iirst removed from the normally gaseous feed mixture byabsorption in liquid isoparaihn as an absorption liquid. This dissolvesthe olefins while allowing the light nonolenic components, principallyhydrogen and methane, to pass through undissolved. The liquidisoparailln rich is oleiin is withdrawn from the absorber and is passedto a catalytic polymerization zone wherein the olenn content is`polymerized catalytically with the isoparailin as a diluent. Theethylene is thereby converted to butylene and if any propylene ispresent, as is usually the case, ethylene and propylene areinter-polymerzed ur co-polymerized to give amylenes or pentenes.Ordinarily. the ethylene is present in such excess that the propylene isentirely consumed in this manner,` substantially no simplepolymerization of propylene to hexylenes taking place. The isoparafnnand the polymer contained in the catalytic polymerization effluent arenow fed to an alkylation zone where the lsoparaflin is alkylated withthe DOlymers or higher-boiling oleflns formed in the polymerization stepto give heavier saturated hydrocarbons having a highly branchedstructure and being in the motor and aviation fuel range of molecularWeight and boiling point. Generally, the al- Another obiect is toprovide a kylate produced is mainly composed of C parafsired, issuitable as feed stock for the present tins and heavier. 'I'he alkylateformed can be invention.

readily separated intoa relatively light fraction, A typical gasobtained by cracking a 25% suitable for use as a high knock ratingblending ethane-75% propane mixture at 6-8 p. s. i. g. and component ofmotor and aviation fuels, and a s at 1400' F. followed by extraction ofC4 and any relatively heavy fraction known in the art as heavierhydrocarbons 'had the following analyheavy alkylate which is verysuitable for use sis:

as a safety fuel, as solvent in paints, varnishes, v M01 per centlacquers and other plastic and coating composi- Hydrogen 18 tions, indry-cleaning, or in insecticides such as lo Met-haue Y 38 fly sprays,etc. mme v n Thusit will be seen that the isoparailin serves Ethylene 29iirst as an absorption liquid to remove the ole- Propane 5 fins from thelighter iixed gases. hydrogen and Propylene 3 5 methane, then as adiluent in the polymerization step whereby undesirable side reactionsare pre- Such a. stream is an excellent feed for the process vented inthe polymerization zone, and then as of the present invention.

one of the reactants, namely, the hydrocarbon The other feed to theprocess of the present which is alkylated in the alkylation step. Noinvention is an isoparaiiln feed. Usually this'is a separation ofolefins from the rich absorption go stream of isobutane since isobutaneupon alkylmedium leaving the absorber is required before ation with thelowest polymer of ethylene, namely the polymerization step and theeiliuent from the butylene, or with the inter-polymer of ethylenepolymerization step is a suitable feed to the alwland 'propylene, thepolymers formed from the\ ation step requiring only the removal ofunreoleiins contained in the preferred olefin stream, acted light gas.g3 gives isooctane and other highly branched oc- Feed stocks tanes,nonanes, etc., which are valuable motor and aviation fuel blendingcomponents and for As the olefin-containing gas stream fed to my othervpurposes wherever heavy alkylate" is deprocoss, I prefer to use anystream rich in ethylsired. However, the feed may comprise isopenene. Thefeed may or may not contain propylene. so tane or even isohexane. It maybe a mixture of The gas may be from any source, for instance theisobutane and lsopentane. Use of such higher waste gas formed in thecracking of heavier norisoparafiins gives a greater yield of "heavyalkylmally liquid material such as gasoline, naphtha. ate. Normalparaiilns corresponding to the isokerosene, gas oil, fuel oil, crudeoil, or the like. paramns may be present in the isoparamn feed. Thecracking gas obtained from vapor phase a5 For example, the presence ofsubstantial quancracking processes is especially rich in oleilns' titiesof normal butane in the isobutane feed which often range up to 60 percent. of the total stream is unobjectionable since such normal bugas andof which ethylene is predominant. The tane functions as an absorbingliquid in the first methane and hydrogen content may range from orabsorption step and as an inert diluent reto 50 per cent of the crackinggas. The com- "40 ducing side reactions in the polymerization stepposition of cracking gases is discussed on pages and in the alkylationstep. The pressure of ex- 114-116 of vol. 1 and pages 139-140 of vol. 2of cessive amounts of normal paraiiin in the iso- Ellis, The VChemistryof Petroleum Derivatives." paraidnV feed maysbe undesirable because itis Ordinarily, such cracking gas is subjected in not feasible toeliminate the normal paramn known treatment for the removal of thevaluable prior to the alkylation step and the presence of C4 and heaviercomponents and frequently. evenl a large amount of normal paraffin mayundethe C; components prior in its use as feed t sirably repress thedesired alkylation reaction. the process ofthe present invention.Thefeedto Both feed stocks should be free of contamithe presentinvention may be derived from the nants orimpurities which wouldinterfere with cracking of ethane or propane or mixtures of thepolymerization or alkylation reactions or ethane and propane which, asis now well-known, which would be objectionable in the finished prod^yields an ethylene-rich gaseous eiiluent which uct. In general, thefeeds are essentially .free usually contains a substantial amount ofpropylfrom sulfur, nitrogen and'. oxygen compounds. ene as well as ofmaterial heavier than C: hydro- For example, the feed stocks should befree from carbons. such an emuent is commonly -treated u sulfur orsulfur compounds such ,as hydrogen to remove the C4 and heavier materialand if sulilde, mercaptans, alkyl suliides, etc.sincethese desired theC; content thereof, although I often impurities are objectionable bothin the catalytic prefer to use a feed from which the propyleneconversions and in the product.

has not been removed.

Atypieeieraekmggasstreamobtamecmme. Mmmm am of gas on fono'm ms: t1 Inthe process of my inven- V l hmm on. the o con ed in the feed, whichole- Hydrogen Y e w iins usually consist oi' ethylene or of a mixtm'eMethane Y 33 7 of ethylene and propylene with the ethylene often Eme 333in excess of the propylene, are absorbed in liq- Ethylene 3 0uidisoparaflin,generallyisobutane,whilethexed me 175 gases, whichusually consist of hydrogen and Propylene 5 7 methane pass throughimdissolved. v Since the Bum Y 9 9 absorption is not selective for`olens as against 'Bum 3 7 n paraiiins, but is based merely on relativevolamm Y v 9 3 tility of the several hydrocarbons present, ethane Y Y vand @ny propane presentv in the feed are dissolved such a stream afterextraction of the C4 and along with yethylene and any propylene.vHowheavier components, which extraction may ever. the presence of theseparaiiins. in later poralso remove a part or all of the C: componente ifde-"I tions ofthe process is not objectionable; on the contrary. theyserve as desirable inert diluent in addition to the isoparaiiln in thesubsequent polymerization step. Generally, they are removed with otherC: and lighter components between the polymerization step and thealkylation step.

The absorption step may be a, simple gas scrubbing operation conductedin the usual vertical column packed or provided with other means foreffecting the desired intimacy of contact such as theusual bubble trays.the cold liquid isoparafdn such as isobutane being injected continuouslyat a point near the top of the tower and descending downwardly thereinin countercurrent to the gaseous olefin-containing feed introducedadjacent the bottom, the undissolved hydrogen and methane continuouslypassing out overhead and the rich absorbing liquid being continuouslywithdrawn from the bottom of the column. With such an arrangement theabsorber pressure and the temperature and rate of introduction ofisoparafnn are so adjusted as to eil'ect solution of substantially allthe oleflns with minimum loss of valuable hydrocarbons (Cz and heavierincluding isoparaln absorbent) in the overhead 0r residue gas. Whereisobutane is used as the isoparailln, the pressure in the absorptionzone may range from 700 to 800 pounds per square inch gauge, theoverhead temperature may be below 40 F., for example, 30 F. ortherebelow, and the rate of introduction of liquid isobutane into thetop of the absorber may be such as to give a mole ratio of isobutane fedin to olefin in the feed ranging from 2:1 upwardly say to 50:1, a rangeof from 2:1 to 10:1 being preferred.

I prefer to provide means for at least partially condensing the overheadfrom the absorber and returning liquid condensate to the top of the co1-umn as liquid reux therefor in addition to the reflux effect provided bythe fresh isoparailin injected thereinto. By condensation of overheadvapors the loss of isoparailln in the outgoing residue gas is cut to aminimum. The condensation should be sulcient tok liquefy substantiallyall vaporized isoparafiln; for example, where the isoparailln isisobutane the condensation is so carried out as to liquefy substantiallyall the isobutane from the overhead gases. If it is found suitable ordeisrable, the condensation may extend down to the C3 hydrocarbons andin extreme cases even down to the Cz hydrocarbons but the expense ofrefrigeration requirements to condense the Czs is prohibitive at thepresent time and the condensation of the Cas is often not commerciallyfeasible under present-day conditions. The condensation ofl thecondensible hydrocarbons from the overhead gases may be carried out inany suitable way as by providing indirect cooling coils in the top ofthe absorber, or by cooling the overhead in a separate cooler, passingto a condensate or reflux accumulator from which the uncondensed gasesare vented in the usual way, and withdrawing the liquid condensate andinjecting it into the top of the absorber.

In many cases I Prefer to operate the absorber as an extractivedistillation column. i. e., to combine rectification and absorption byproviding means for rebolling the kettle product prior to its withdrawaland means for partially condensing the absorber overhead as justdescribed. The principles underlying extractive distillation are nowwell understood by those skilled in the art and need not be detailedherein. When extractive distillation is employed for separating theoleflns from the methane and hydrogen in practicing my invention, theolefin-containing feed is inpolymer produced is in the Ce-Cs range.

example, where the olefin consists substantially of ethylene, it ispreferred that the polymerizal 6 troduced into the middle ofthe absorbercolumn rather than into Aits bottom as in the case where simple gasscrubbing is practiced. In extractive distillation the bottomtemperature wil1 be the boiling point of the kettle product at thecolumn operating pressure.

Polymerization step The isoparamn containing dissolved olefin withdrawnfrom the absorber as bottom or kettle product is next passed to a unitwherein the olens -are polymerized to higher-boiling olens. 'I'heisoparaiiln functions as anv inert diluent and to repress undesired sidereactions during the polymerization, and also to enable liquid phaseconditions to be maintained therein without excessive pressures and eventhough the polymerization temperature be above the critical temperatureof the ethylene or-of the ethylene and propylene.

It is preferred to conduct the polymerization under such conditions thatsubstantially the sole reaction is one of simple polymerization of theolefin. It is also preferred that conditions be so adjusted that a majorportion of the olefin For tion convert it principally to butylene andwhere the olefin consists essentially of ethylene and propylene thatprincipally butylene and amylene be formed. Since the propylene isusually present in minor amount, conversion thereof to amylene byco-polymerization, mixed polymerization or inter-polymerization with theethylene which is present in excess, is relatively easily accomplished.Where propylene is in excess of ethylene the excess may be converted tothe dimer.

Polymerization primarily to olefin in the Ci-Cs range is preferred inorder that upon alkylation of the isoparaflin with the polymerthe'alkylate will not be unduly heavy but instead will be primarily inthe gasoline range. To this end, polymerizationconditionsV are soadjusted as to effect principally dimerization and simpleco-condensation of ethylene with propylene. If production of heavyalkylate as the principal or sole product is desired, thenlpolymerization of the olefin to higher olens than Cs may be effected.However, ordinarily the extreme upper limit of polymer range will bedecylene since alkylation of the usual isoparaflin with olefin polymerabove decylene gives aikylate having more than 14 carbon atoms permolecule for which there is little demand.

The polymerization is conducted catalytically. The selection of suitablecatalysts and suitable reaction conditions such as pressure,temperature, contact time, ratio of hydrocarbon to catalyst. and otherfactors will be obviousto those skilled in the art in the light of thisdisclosure. In general, the polymerization of ethylene requires somewhatmore .active catalyst or more drastic reaction `conditions than thepolymerization of its homologs. I prefer to effect polymerization of theethylene by means of a more active catalyst which effects the desiredconversion under conditions such that, with the isoparailin present inamount required to effect the absorption, a minimum of side reactionstakes place in the polymerization zone. A catalyst which I have found tobe exceptional is that of activated nickel oxide supported on a suitablecarrier as disclosed more fully in the copendingV applications of G. C.Bailey et al., Ser. No. 435,888,

assenti.

filed March 23, 1942 (now U. S.Patent 2,381,198

granted Alllllt 7, 1945), and Sel'. No. 599,536,

filed June 15. 1945. I'he patent applications men- 1 thereof are herebyincorporated by reference. A

preferred lcarrier is that disclosed in the secondmentioned application,namely. silica gel either by itself or preferably promoted with a smallamount of alumina as by impregnating the still wetI or only partiallydried freshly precipitated silica gel with an aqueous solution of asuitable aluminum salt' such as aluminum sulfate or nitrate. Use ofsupported nickel oxide catalysts of the types disclosed in the abovementioned applications is especially advantageous in the practice of-this step of my invention because such catalysts smoothly effect simplepolymerization of ethylene which very frequently is the sole or theprincipal olefin present in the feed. v

The polymerization temperature may vary within a rather wide range butwill generally not be much lower than about C. nor substantially aboveabout 225 C. It is preferred to polymerize with the range of about 50 to150 C. Atmospheric temperature, about 24 C., is often used. Temperaturesof at least about 100 C. ranging up to 200 C. may be superior since atsuch levels polymerization is accelerated without undue side reactions.Above a polymerization temperature of about 200 C. hydrocarbons otherthan oleiln polymers begin to be formed. The polymerization isordinarily conducted at temperatures not over 150 C. It is carried outin the absence of hydrogen or other reducing agent.

High pressures favor the polymerization reaction, but under suitableconditions the reaction may be carried out under a very wide range ofpressures, from as low as atmospheric or below to as high as 2000 p. s.i. or above. Although high pressures increase the'rate of polymerizationthey also increase the average molecular weight of the polymer formed.Accordingly, it is ordinarily preferred to conduct the polymerization attemperatures of not over 200 p. s. i.

The polymerization may be carried out in either liquid or gas phase.Ordinarily liquid phase operation is preferred. Accordingly, thepresence of the isoparaflln in the feed to the polymerization step isadditionally advantageous since it enables liquid phase conditions to bemaintained much more readily and at desirably moderate pressures.Pressures such as to insure substantial or complete liquid phaseoperation are preferred. Liquid phase operation facilitates control ofreaction temperature and contributes to catalyst life by diminishing thedeposition of high molecular weight, or other non-volatile or insoluble,materials on the. catalyst surface. When polymerizing at temperaturesabove the critical temperature of the olefin, the presence of the inertisoparaiiln, which was used as an absorbing liquid and is subsequentlyused as the alkyiated hydrocarbon, facilitates the maintenance of liquidphase conditions. When polymerizing at temperatures below the criticalof the olefin, the isoparailln performs its functions of minimizing sidereactions and serving as an inert diluent.

In the relatively rare situation where poly- 'merization is vcarried outwith the hydrocarbons in the gas phase, conditions should be such thatthe exothermic heat of reaction does not cause ve local overheating ofthe catalyst or a general rise in temperature above the desired op- 8erating range. This can be .accomplished by suitable design -of acatalyst chamber to allow good heat transfer, and by controlling therate of introduction of charge stock.

The contact time in the polymerization zone may vary over a wide range.A time as low as 30 seconds at atmospheric pressure and in the preferredtemperature range is sufcient to polymerize the olens appreciably.However, higher extents of conversion are possible when a longer contacttime and/or higher pressure are utilized. Contact times of 3 and even 12hours may be employed but are ordinarily too long to be commerciallyfeasible. Contact times suillcient to polymerize at least 75% of theolefin are preferred in order to minimize recycle or auxiliarypolymerization.

Since the preferred nickel oxide catalysts are readily deactivated orpoisoned by 'various materials such as sulfur compounds, carbonmonoxide. some halogen compounds, organic oxygencontaining compounds,and the like, it is desirable, in order to secure satisfactory catalystlife,

vto exclude such materials from the polymerization system. This ispreferably done by excluding them from the feeds to the absorbing step.Any suitable means for removing such materials from the feed may beemployed.

Where the polymerization catalyst is a solid material it may be arrangedin the form of a bed through which the polymerization feed is passed,usually downwardly. Alternatively, the catalyst maybe suspended in thehydrocarbon liquid or vapors in the manner in which so-called fluidcatalytic conversions are effected. Known means for regenerating thecatalyst is provided regardless of. the form which the catalyst takes.

Instead of a nickel oxide catalyst, I may use any other catalyst whichis capable of effecting the polymerization of ethylene. Such othercatalysts may be either known now or discovered in the future. Thereaction conditions discussed in detail above apply particularly to thepreferred activated nickel oxide catalyst. With other catalystsdifferent polymerization conditions may be desirable. As an example ofanother type of catalyst, I may use boron fluoride and a nickel promoteras disclosed in VOtto et al. 1,989,425. Another catalyst is aluminumchloride.

The eilluent from the polymerization step may be subjected tofractionation or other means of separation to remove all materiallighter than C4 leaving a fraction containing C4 and heavier includingisoparailln and butylene and all other polymeric material formed in thepolymerization step. If desired it may be further fractionated toseparate material heavier than a predetermined level of molecularweightv or boiling point. For example, if the polymerization produces asmall amount of heavy oily or waxy polymers it is often desirable toremove these and thereby prevent them from entering the alkylation stepwhere they would give undestrably heavy alkylate. The unpolymerizedolefin separated from the polymerization eluent may be passed to anauxiliary polymerization unit and there polymerized catalytically, theresulting polymer being merged with the polymer from'the mainpolymerization unit for passage to the alkylation step. If desired.isoparailln may be admixed with the olefin feed to the auxiliarypolymerization unit whereby the above-detailed advantages of itspresence in the main polymerization unit are attained. If desired theolefin-containing stream separated from the main polymerization eluentaesaosi may be recycled to the absorption step or directly to the mainpolymerization step.

l Aller/lation step line boiling range up through heavy alkylate"ordinarily having not more than fourteen carbon 4atoms per molecule.-

The alkylation step is conducted in a manner known per se. It is almostinvariably carried out.

catalytically. It is ordinarily preferable to employ an inorganic acidsuch as substantially anhydrous hydrouoric acid. or concentratedsulfuric acid as the alkylation catalyst although any other suitablealkylation catalyst known now or discovered in the future may beemployed, since the alkylation step does not per se constitute myinvention. Many other alkylation catalysts are known such as aluminumchloride, aluminum chloride complexes, boron fluoride, etc.

The alkylation step is conducted in a manner well within the presentskill o! the art and conditions for this step need not be described indetail. Sumce it to say that the alkylation ls conducted in such a way,that the oleilns alkylate the isoparaflln to give the desired product.

The alkylation enluent is treated in known manner as by fractionation,etc. to recover recyclev and product streams. Usually a phase ofcatalyst is recovered for recycle to the alkylation unit, a portionbeing passed to a regeneration or re-run unit. Likewise a phase oi.'unreacted isobutane is recovered i'or recycle to the absorption unit.

Many advantages are attained by the present invention. The principaladvantage is that cheap olefins especially ethylene in readily availablecracked gas streams are converted to very valuable alkylate in a simpleand economical manner. Other advantages are that a single material,namely, the isoparafiln, performs a number ot valuable functions in asimple and peculiarly advantageous manner, namely, as liquid absorbentin the iirst step, as diluent and liquetying medium in the polymeriation step and as major reactant in the alkylatio stage. Anotheradvantage is that a large excess of isoparaiiin to olen 'is maintainedinthe absorption step and is therefore maintained in the polymerizationand alkylation steps whereby very undesirable side reactions areprevented. This large excess of isoparamn is particularly advantageousin the alkylation step since it prevents oleiln polymerization andimproves the alkylate quality. Many other advantages of my inventionwill be apparent to those skilled ln the art.

Referring now to the accompanying drawing,

L the olefin-containing gas stream is charged to an absorber 2 throughline I. 'I'he absorber is operated under such conditions (for instance,F. overhead and '760 p. s. i.) that most of the C2 and heavierhydrocarbons are absorbed in the liquid isobutane supplied at the top ofthe absorber 2, while lighter hydrocarbons such as hydrogen and methaneare removed as gases. Isobutane which will be used in the reaction lateris used as the absorption medium and as the reilux for the absorber 2being added through line l in' a mole ratio 012:1 to 50:1 of olefin witha ratio ci 2:1 to 10:1 preferred. Abmrber 2 may 10 be provided with areboiler 2A as shown to effect fractionation, thus serving to enectextractive distillation. It desired, the overhead may be cooled ordephlegmated to condenseCz and heavier, or C: and heavier, or Ci andheavier which is ted to the top of absorber 2 as reilux. Usually it willbe desirable to condense and return only the Ci (and any heavier)contained in the absorber overhead, to avoid excessive refrigerationrequirements. The provision for reuxing the tower is indicateddiagrammatically on the drawing by the showing of an indirect refluxcooler 2B, although it will be obvious that any other suitable means foreil'ecting the desired result may be employed. The fixed gases such aslhydrogen and methane are removed at I and disposed of in any desiredmanner. '-I'he isobutane and absorbed gases are removed through line land charged to polymerization reactor or reactors i. I'he reactors 6 maybe operated in any desired sequence; two or three reactors 8 may beoperated in parallel or series while the other one or 'two chambers arebeing regenerated with an oxygen-bearing gas. Ethylene can be convertedt0 predominantly butylenes, and if propylene is present copolymerizationto amylenes may also be eiiected by the use ot any suitable catalyst. Apreferred catalyst is one of activated nickel oxide on a suitablecarrier such as is described in the above-mentioned copendingapplications of G. C. Bailey et. al., Ser. No. 435,888, filed-March 2 3,1942 (now Pat. No. 2.381.198), and Ser. No. 599,536, nled June 15, 1945.

'Ihe emuent from the polymerization reactor is withdrawn through line 'Iand charged to a sep arator l' which conveniently takes the form of a'conventional fractional distillation column and which is operated undersuch conditions that C: and lighterhydrocarbons are removed through lineI. The disposal of this material will be gov-- erned by the amount ofolefin present and the value or the olefin. 4If the olefin content ofthe gas is low it may be removed through line 25 and disposed of in anymanner. It the oleiln content of the gas is high a portion of the gasmay be returned to the feed to the absorber 2 through line 2l and theremainder vented through line 25 or all of thev gas may be charged to anauxiliary polymerization unit 21 similar to 0 but adjusted as to size.The eilluent from the polymerization unit 21 is withdrawn through line28 and charged to a separator or fractionation column 29 from whichpolymer is removed through line 3l and mixed with the eiiiuent from theseparator 8 in line II. Residue gas from separator 29 is removed throughline 20. The isobutane and oleilns are withdrawn through line II andcharged to an alkylation unit I3. Any type alkylation unit may be usedsuch as an HF or sulfuric acid unit operated underconditions known tothe art. The eiiluent. from the alkylation unit I2 is charged to aseparation unit I5 through line I4. Separation unit II may comprise aseries of iractlonal distillation columns to effect the indicatedseparations. Catalyst carried out with the hydrocarbon may be reclaimedand returned to the reactor I3 through line I6. Excess isobutane isremoved through line I1 and may be combined with fresh isobutane throughline 22 and returned to the absorber 2, the separator 8 or thealkylation reactor I3. Any n-butane present may be removed through lineI2 and disposed of through line II or charged to an isomerization systemthrough line 22 to be added to the recycle isobutane from line l1. Lighthydrocarbons in the motor fuel and/or aviation fuel boiling range arewithdrawn from the separation unit I through line 21 and heavyhydrocarbons boiling above the motor fuel boiling range are withdrawnthrough line 2l.

Example A hydrocarbon stream containing mostly ethylene and methanetogether with smaller amounts of hydrogen, ethane, propylene. andpropane, is counter-currently contacted at 30 F. and 'Z50 p. s. i. withisobutane in an absorption tower. A gaseous mixture containing mainlyhydrogen and methane is withdrawn at the top of the tower. and a liquidmixture of isobutane and ethylene containing minor proportions ofethane, propylene and propane is withdrawn from the bottom. The molratio of isobutane to ethylene in the latter mixture is approximately 8:l.

The isobutane-ethylene mixture is then passed through a catalyst chamberlled with a polymerization catalyst having the composition 1.5 per centnickel oxide, 90 per cent silica gel, and 8.5 per cent alumina.Conditions for this treatment are; temperature, 120 F.; pressure,suiiicient to maintain liquid phase; space velocity, 2 liquid volumesper volume of catalyst per hour. Approximately '10 per cent of theethylene is polymerized, and of this amount approximately 80 per cent isconverted'to butylenes. The polymerization eiiluent is passed to afractionation column from which ethane, unconverted ethylene, propylene,and propane are removed as an overhead fraction and recycled to theabsorption tower.

The kettle product from the fractionator is passed to an alkylationreactor provided with a motor-driven stirrer and is intimately contactedwith an equal volume of anhydrous hydrofiuoric acid. The alkylationconditions are: temperature, 100 F.; pressure, sumcient to maintain thereactants in the liquid phase; contact time, 10 min.; mol ratio ofisobutane to olefin, at least 16:1: acidity of the acid phase, 90 percent. The eflluent from the alkylation reactor is passed to a settler inwhich it separates into an acid phase, which is recycled to thealkyiation reactor, and a hydrocarbon phase. Dissolved hydrofluoric acidis removed, as a minimum-boiling azeotropic mixture with isobutane. fromthe latter phase by distillation. Organically combined iluorine isremoved by contacting the acid-free hydrocarbon phase with calcinedbauxite at about 180 F. The substantially iluorine-free hydrocarbonphase is then passed through a series of fractionators from which thefollowing fractions are obtained: a

fraction, comprising chiefly isobutane, which is recycled to theabsorption tower; a fraction, ccmprising hydrocarbons in the motor fuelboiling range, chiey octanes. which is withdrawn as the main product ofthe process; and a fraction, comprising hydrocarbons that boil above themotor fuel range, which is withdrawn from the system.

I claim:

l. A process of converting normally gaseous olefin comprising mainlyethylene contained in a gaseous mixture containing other normallygaseous components into heavier hydrocarbons having molecular weight andboiling point in the motor and aviation fuel range which comprisesabsorbing said olefin comprising mainly ethylene from said normallygaseous mixture in liquid isoparaitln in an absorption zone whileallowing other tion zone, said isoparafiin serving as a diluent andenabling maintenance of liquid phase in said polymerization step,withdrawing the resulting mixture oi said isoparai'lin and saidhigher-boiling olefin and feeding it to an alkylation zone. and therealkylating said isoparailln with said higherboiling olefin to giveheavier hydrocarbons having molecular weight and boiling point in themotor and aviation fuel range.

2. The process of claim 1 wherein the polymerization eiiluent iswithdrawn from the polymerization zone and is subjected to separationinto a C3 and lighter fraction and a fraction of said isoparamn andhigher-boiling olefin which is employed as the' feed to said alkylationstep.

3. The process of claim 1 wherein said liquid isoparailin is supplied tothe top of said absorption zone in an amount such as to give a moleratio to oleiin in the gaseous mixture fed to said absorption zone of atleast 2:1.

4. The process of claim 1 wherein the bottom of said absorption zone isreboiled, the feed thereto is supplied at an intermediate point therein,said liquid isoparamn is supplied to the top thereof in an amount suchas to give a mole ratio to olefin in the feed of at least 2:1, theoverhead gases are cooled to effect condensation ofl at least the majorportion of the C4 content thereof and the resulting condensate is fed tothe top of the absorption zone as redux therefor.

5. The process of claim l wherein said polymerlzation is eiected with asolid catalyst comprising nickel oxide supported on a carrier andactivated by heating in an oxygen-containing atmosphere at a temperatureof between 400 and '100 C.

6. The process of claim l wherein said olefin consists essentially of amajor proportion of ethylene and a minor proportion of propylene and isconverted substantially to butylene and amylene in said polymerizationstep.

7. A process of converting ethylene contained in a normally gaseousmixture containing other normally gaseous components into branched chainoctane which comprises absorbing said ethylene from said normallygaseous mixture in liquid isobutane in an absorption zone while allowingother normally gaseous components to pass through undissolved,withdrawing the resulting solution of ethylene in liquid isobutane fromthe absorption zone and feeding it directly to a polymerization zone,effecting catalytic liquid phase polymerization of said ethylene tobutylene as the principal reaction in said polymerization zone, saidisobutane serving as a diluent and enabling maintenance of liquid phasein said polymerization step, withdrawing the re.

sulting mixture of said isobutane and polymer including butylene fromsaid polymerization zone and feeding it to an alkylation zone, and therealkylating said isobutane with said butylene with an inorganic acidcatalyst selected from the group consisting of substantially anhydroushydrofiuoric acid and concentrated sulfuric acid to give branched chainoctanes.

8. A process of converting ethylene contained in a normally gaseousmixture containing methane and hydrogen into branched chain octaneswhich comprises absorbing said ethylene from said normally gaseousmixture in liquid isobutane in an absorptionzone while allowing othernormally gaseous components including the methane and hydrogen to passthrough undissolved, withdrawing the resulting solution of ethylene inliquid isobutane from the absorption zone and feeding it directly to apolymerization zone, effecting catalytic liquid phase polymerization ofsaid ethylene to butylene as the principal reaction in saidpolymerization zone, said isobutane serving as a diluent and enablingmaintenance of liquid phase in said polymerization step. withdrawing theresulting4 mixture of isobutane and butylene from said polymerizationzone and feeding it to an alkylation zone, and there alkylating saidisobutane with said butylene with an inorganic acid catalyst selectedfrom the group consisting of substantially anhydrous hydroiluoric acidand concentrated sulfuric acid to give branched chain octanes.

9. The process of claim 8 wherein said polymerization is eiected with asolid catalyst comprising nickel oxide supported on a carrier andactivated by heating in an oxygen-containing atmosphere at a temperatureof between 400 and '700 C.

10. A process of converting ethylene and propylene contained lin anormally gaseous mixture containing methane and hydrogen into alkylatein the motor and aviation fuel range of molecular weight and boilingpoint which comprises absorbing said ethylene and propyleneA from saidnormally gaseous mixture in liquid isobutane' in an absorption zonewhile allowing other normally gaseous components including the methaneand hydrogen' to pass through undissolved, withdrawing the resultingsolution of ethylene and propylene in liquid isobutane from theabsorption zone and feeding it directly to a polymerization zone,effecting catalytic liquid' phase polymerization of ethylene andpropylene predominantly to butylene and amylene -by simple andinter-polymerization as the principal reaction in said polymerizationzone, said isobutane' serving as a diluent and enabling maintenance ofliquid phase in said polymerization step, withdrawing the resultingpolymerization eiiluent. separating Cs and lighter components from amixtureof isobutane and the polymer formed in said polymerization stepand feeding said mixture oi' isobutane and polymer to an alkylationzone, and there alkylating said isobutane with said polymer with aninorganic acid catalyst selected from the group consisting ofsubstantially anhydrous hydroiiuoric acid and vconcentrated sulfuricacid to give heavier hydrocarbon in themtor and aviation fuel range ofmolecular weight and boiling point.

11. The process for the preparation of an `alkylate comprisingprincipally branched chain oc- 14 tanes from ethylene. contained incracked gas containing same in dilute form in admixture with hydrogenand methane together also with some ethane and a small amount ofpropylene relative to the ethylene. said gas being free from C4 andheavier components, which comprises absorbing the ethylene and propylenefrom said gas by intimately countercurrently contacting said gas in avertical scrubbing zone with liquid isobutane in an amount such as togive a mol ratio of lsobutane to ethylene plus propylene in said gas offrom 2:1 to 10:1 at a top temperature below 40 F. and a pressure of from100 to 800 pounds per square inch gauge and thereby effecting solutionoi' substantially all of said ethylene and propylene in said gas in saidisobutane while causing the hydrogen and4 methane to pass throughundissolved, passing the resulting liquid isobutane containing dissolvedethylene and proof propylene with ethylene to amylene as the; 3

principal reactions, eifecting said polymerization at a temperature offrom 24 to 150 C. with a solid catalyst consisting of nickel oxidesupported on a carrier and activated by heating in an oxygen-containingatmosphere at a temperature of from 400 to 700 C., the isobutane servingas a diluent and enabling the maintenance oi' liquid phase in thepolymerization step, fractionally distilling the polymerization effluent-to separate same into a fraction oi.' the material lighter than Crhydrocarbons and a fraction containing the isobutane and the butyleneand the small amount of amylene formed in said polymerization step,passing said last-named fraction to an alkylation step and therealkylating said isobutane with said butylene and amylene with analkylation catalyst composed oi' an inorganic acid which is incapableoi' effecting .alkylation of isobutane with ethylene, thereby formingalkylate compris ing principally branched chain octanes, and recoveringsaid alkylate comprising branched chain octanes from the alkyiationeiiiuent as the product of the process.

HAROLD T. QUIGG.

REFERENCES CITED The following references are of record in the ille oi'this patent:

UNITED STATES PATENTS

